The broad focus of the proposed research is children's executive functioning (EF) and its relation to social-cognitive development. EFs include self-regulation, planning, response inhibition, and resistance to interference. The acquisition of EF skills in the preschool period is associated with a host of social (e.g. emotion regulation, conscience, and social competence) and cognitive (e.g., intelligence, attention, memory, and reading comprehension) abilities. In addition, deficits in EF increasingly have been linked to the disorders of autism and Attention Deficit Hyperactivity Disorder. Hence, it is of considerable importance to determine whether and low EF mediates young children's social and cognitive functioning. The specific claim under investigation is that EF skills such as inhibitory self-control, mediated by prefrontal cortex changes, are critically related to children's representational abilities in development. Evidence suggests that EF may contribute to both the emergence and expression of mental representational skills, such as those required for problem, solving and reasoning about mental states like beliefs (i.e., "theory of mind"). The locus of inquiry in this proposal is one of the earliest and most observable (yet understudied) manifestations of children's capacity for a representation: pretense. A number of cognitive theories exist to explain how it is that young children, who would seem to have much to learn about the real world, can engage in an extensive amount of pretense. Inhibitory control, a critical component of EF is proposed as a common denominator in these theories. In addition, past research studies have directly or indirectly indicated a positive relation between self- control (e.g., waiting ability) and pretense/fantasy in children. Recent preliminary data collected with toddler and preschool children support these findings. The proposed research therefore aims to examine more thoroughly the relation between individual differences in children's EF and pretend play skills. This aim will be achieved in two ways: first, in a correlational study investigating whether well-established measures of inhibitory control are related to performance on a variety of pretense measures in 3-year olds, independent of effects due to age, sex, verbal ability, and working memory capacity; and second, in a study measuring the extent to which experimentally manipulating one of these constructs has systematic effects on the other. Specifically, a pretense context (symbolically represented rewards) will be used in an attempt to enhance children's self control.